*,
*::before,
*::after{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html{
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body{
    min-height: 100vh;
    min-height: 100dvh;
    background: #FFFFFF;
    color: #3A3F47;
    font-family: "Open Sans", system-ui, -apple-system, Segoe UI, sans-serif;
    font-size: 1rem;
    line-height: 1.75;
    font-optical-sizing: auto;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
    padding: clamp(1.5rem, 5vw, 4rem) clamp(1.25rem, 5vw, 2rem);
    border-top: 3px solid #1D7FC4;
}

header,
main,
footer{
    width: 100%;
    max-width: 44rem;
    margin-inline: auto;
}

header{
    padding-bottom: 2.25rem;
    margin-bottom: 2.75rem;
    border-bottom: 1px solid #E3E8EE;
}

.back{
    margin-bottom: 1rem;
    font-size: 0.9rem;
    font-weight: 600;
}

h1{
    color: #171A1F;
    font-size: clamp(1.9rem, 5vw, 2.6rem);
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.02em;
}

.updated{
    margin-top: 0.9rem;
    font-size: 0.85rem;
    color: #666D77;
}

.updated strong{
    color: #3A3F47;
    font-weight: 600;
}

.summary{
    margin-top: 1.75rem;
    padding: 1.15rem 1.35rem;
    background: #EAF3FA;
    border: 1px solid #BBD7EC;
    border-radius: 10px;
    color: #3A3F47;
    font-size: 1.02rem;
}

main{
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

section{
    width: 100%;
}

h2{
    color: #171A1F;
    font-size: 1.2rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    line-height: 1.35;
    margin-bottom: 0.9rem;
    padding-bottom: 0.6rem;
    border-bottom: 1px solid #E3E8EE;
}

.toc{
    padding: 1.1rem 1.35rem;
    border: 1px solid #E3E8EE;
    border-radius: 10px;
}

.toc h2{
    margin-bottom: 0.7rem;
    padding-bottom: 0;
    border-bottom: 0;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: #666D77;
}

.toc ol{
    margin: 0;
    padding: 0;
    list-style: none;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.35rem 1.5rem;
}

.toc li{
    padding-left: 0;
    font-size: 0.95rem;
    line-height: 1.5;
}

.toc li::before{
    content: none;
}

section{
    scroll-margin-top: 1.5rem;
}

::selection{
    background: #BBD7EC;
    color: #171A1F;
}

section > p + p,
section > ul + p{
    margin-top: 0.9rem;
}

ul{
    margin-top: 0.9rem;
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
}

li{
    position: relative;
    padding-left: 1.5rem;
}

li::before{
    content: "";
    position: absolute;
    left: 0.15rem;
    top: 0.72em;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #1D7FC4;
}

strong{
    color: #171A1F;
    font-weight: 600;
}

a{
    color: #1971AF;
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: color 0.15s ease, border-color 0.15s ease;
}

a:hover,
a:focus-visible{
    color: #15618F;
    border-bottom-color: currentColor;
}

a:focus-visible{
    outline: 2px solid #1D7FC4;
    outline-offset: 3px;
    border-radius: 2px;
}

footer{
    margin-top: 3.25rem;
    padding-top: 1.75rem;
    border-top: 1px solid #E3E8EE;
    text-align: center;
    font-size: 0.85rem;
    color: #666D77;
}

header,
main,
footer{
    transition: opacity 0.3s ease;
}

html.js:not(.is-ready) header,
html.js:not(.is-ready) main,
html.js:not(.is-ready) footer{
    opacity: 0;
}

@media (prefers-reduced-motion: reduce){
    header,
    main,
    footer{
        transition: none;
    }

    html{
        scroll-behavior: auto;
    }
}

@media (max-width: 40rem){
    .toc ol{
        grid-template-columns: 1fr;
    }

    .summary{
        font-size: 0.98rem;
    }

    h2{
        font-size: 1.1rem;
    }
}